SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8424a1930e0f7f10aac89129a39f395742010b4c4bd65d3056fae83a9847dd2' 
  AND token = '5aFCLDQ6Gcl7sbYHUbINjVjkGxY8uLUjL6WCwr3rD+Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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