SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1981b24b0df9ac17a7cf50054e12f196edbf89c08bf3a13418c8f3c64d6178d5' 
  AND token = 'uNQ9HWmCM9sLhiXXy+IDIHOPStGcpT186iPdbve+P64=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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