SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9cf25435803ac9cc9681db325d15a8542ed5640442531f0d683deacfa70445d2' 
  AND token = 'uR8dQ+GysFc6GRqYABgJtyEZJEXiDBpasNzLPOyqlSk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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