SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '13dc1dfc5fb8c6e3622ab368c2be68c8493f1937eadfa87d9443be5b54fe5371' 
  AND token = 'n5Wv7pk/JWV2kKNx2cK8FGBhzmNd4BDAHD9TCOqFTaY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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