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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '279c24f2ac46f5be40ff9fda901d8734d64df2dee746a29cb1cb079528404c1c' 
  AND token = 'ljIqfOqxA39NlNZ0mhMQ5g+kkq0VOdK3uCuccFkFQAM=' 
  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"
    }
  }
}