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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b8c3d54a1d74e775b2ca5cc8b8e762c7f2c5680692491e8d862d402d6927043' 
  AND token = 'P81jFxaIQ+DxNXCht96YQ+dJN3jeNDWTpUAQV5rHhgY=' 
  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"
    }
  }
}