SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e5253bb385fb9935e33ff5f583a1328ccb04bda8611ded1cda6f15343762deed' 
  AND token = 'Nos6cbiFM5slAexnQp2BDKQIctjCwf+KM3buFPbVIao=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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