SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6cf148ac970c01a6cc744086ecfc3924cdde5b52578d9e6a23f55019fbe47a9' 
  AND token = '7dU1hK928kDKBzmiY0LYTDjmIQ6R6WryXNthxt2xx5M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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