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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b0d8666a6cc1bdf64a3de90096906705e707b6d9d13dfb6538374c08cf741c2' 
  AND token = 'ymnmScN7bK4XfeqbiJQ65G7ud6ZuqEnUwMqQr/Rpmjk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}