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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'c7ff1d9790fd3005bb68df2c9eb171127c0c29600a0729470b0b3ee8d4e38aa5' 
  AND token = 'As61QZMxdcof/zqw5xT7ajDyaSCSXpm5Dvxip0ym8C0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}