SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '74e8c9f3356eec4e193e3c83306816baf7ef7d1135a44aa2c4f0d3ccc3ba9331' 
  AND token = 'uNRqNimOyNkro295eYpwmQzoK5rMA36vbdPiRVVydFI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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