SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c1b3f5ae44d4f788908cdc2e81b7be75fa6e6cbac9ad778a45676cf866cffb70' 
  AND token = 'lx4RnpyEnG+uaLzwvRZbI2JZ9TOL6nmo1tJBVip/qTY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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