SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c2dceb46be5316536d846b72b355eadb802fef8d2a2b784b6e8722b82a51e75' 
  AND token = 'yRRE2QztL08ldJxoXTVIEiimIhOWH16A1KNt59X3Kp8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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