SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8f3f17ef25c82a932083410a5be9cf7942f3d5bb96a310e29f956f47aa0a06c' 
  AND token = 'J1u+Z6YmU4vUcIhdVhPUWWaLaeONc2REaOjSzw7HZvY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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