SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6664487e057d33b0267eb5c2484e3ccc1a08eca6660c9692a98593385460ed4' 
  AND token = '/uzCqvz5rLWVBisBFCIhpftMY4EYDHjscxo8qShL9GY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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