SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '53b374209a09decc8b3daf12885017ccfc7b1cd939f56023f7462c8961217685' 
  AND token = 'kIFbjyOYrAc/9P/OxdCQgZPRIN6p/NBoms4xkoKrRts=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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