SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4694c942fdd29c457befb16b26a9802ac8208483c2dc8a06ff05b9e47418aa4d' 
  AND token = 'TjOnMval2afo/IuBl/oQML9tNWI5ig+BPs+s8PxC1LE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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