SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '349ddc7db27990538262c5edb0b8715a51d055912b47824887ab51acb4018937' 
  AND token = 'FjeuJUOyPqW2KMgBylbzjFSe/jE9jvbMEqmcD5c3hwY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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