SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bcfc15c588f7ff246874fe637633f2c898b8bed63ffb7eadaeb62912998b8f26' 
  AND token = 'nhqRlai54rqHQwsdUqFvfvliRk5HB8dUiwpiZIXR9Bs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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