SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b3776e31a7aa484f228d9536cd98d5c30cc459cfc8ef3ea8cec520d7b743276' 
  AND token = '4b5QaVhJhSsn4WKpug/y2oXez4hTSr4rree2aPB15i8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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