SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29117389b35675bc1dd97d0733954f0bd87c9fab9431adf66c1e58f29a0be6cf' 
  AND token = 'LRwKwvmU3Io2JmxI8fZKcBqmZtfljIfAYCEfI2z8F4Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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