SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42c1ffdf0a325c5e1b9128ef58978c6ead70f1b5d8ab7530ec7a62f8387852ca' 
  AND token = 'Ii9cp4ft2vSXrYcouYNciZ4ifzDKxt+NB91ylqWwA8o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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