SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6589c655f7fe1d5913bb7fa1ca5e845b59c88adcd519649eaa6672dd6497aff' 
  AND token = 'lm43uY6nBdGsm5ApBZrQKvqkxG4pIVJYMJ6nAKrMDhg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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