SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c424d4d080f209b3c94b860a0b460452ffcb1230733610941c81b5718a8a6914' 
  AND token = 'tT+YDPC4OzzQApFh+mYyK8LLH7HTnrIWaXJcSyCKddc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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