SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50559847f30d8b2a16b1528fce8a1eab2d663c25948543df28964a05c7b9ee2f' 
  AND token = 'TQujOkH4mV6YRMsU0ZWTItoSffopKmhx44Yzr5uh2oU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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