SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '760531962cb115f1f2c77dee7551be76173ec1e0226c30a59c36ece94fb984a0' 
  AND token = '/qlwJGPgKuKI4xMMX7jBSp/gtZdCG/QI+Kl0d6P2l8I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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