SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f014f27a9bed3354f9e5058d340cbb5351e49bf7bf2acbef939b6045d2a76c69' 
  AND token = 'mZvsXQKFwGIIILt6n7qMSpcpAlSj+moXKoE4u+yXRyg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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