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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb66568a2e3ecff217ec5bc2d9a0fcf6a9a874ac0735bd4d5c7cf8e49ac5cab1' 
  AND token = 'ep4tJePgGUJB0wz15AuIWsmSpDooTJVnqjw+rms1auM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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