SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c0fe9421e6143eb3325d12826bfde51d36a13ce0d2398de4aef77ff345a24d4d' 
  AND token = 'pMaCiM7y/w+TdumdjBcgO8V9cm74MOtLYq79eurccYI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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