SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ab6456abcead2d687ced480555848b6de1fa50daa1765e28460aa18454aafcb6' 
  AND token = 'F0U9iW3pXwfEYnvDd0b1j4Ac7dT9zWYk7b5ihaKSr7E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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