SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd484ed8456b5068ee0afa863a64c474e715623340588f2be5a462a8121a191db' 
  AND token = 'rRq2tlPsxJ1P8JGQV5+jEckd0QEjqPpYOwaahOqWzck=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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