SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27dc403239e10c088b1f938efc9519cdfed00ac138a68aa781a41872b4c82530' 
  AND token = 'ZrNTtwQ14tKMJCQN5XJH99CageGU8HdMWSKEWYkWjso=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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