SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd6f68ba19c132da4a706c18c604a304d42971a88e81eb831e40cf5ed2d53102' 
  AND token = 'ErfHRzOgpcxqDQM6mGf1LWSXedceAhXkkMmXSDZc1J4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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