SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1124543857a994c37942dde031d17805458d15a64243838a1612622e4fe2eaf9' 
  AND token = 'PRIYFrUQhO1L+0fhfoq6kJVNoZ2UCPLlz/iOGfnQ5C0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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