SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '738db4a244d4db6751f3c395594a1c15af57a4b26cb858f2fca4ab2c6795e8f9' 
  AND token = '+f6v/1rjOikfPJP6wAAHpD/yBuoU0JwkVWH/XzRZw3U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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