SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b18b619903be628a66d4fd2ffdf0d7746683ba28e5a80e0ff8fbe2f9a58b105e' 
  AND token = 'YwB/GEJGD8Nak12BJ5DAzqKRTPHKL49blP9qcL3aPaQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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