SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31e9814a4bdf2c9cb6ee8aa851418f71ef69b2998716f5339a137595212ad899' 
  AND token = 'Wuq5CqFujIe20Y0FiWz8ZO+D9fP+G0ummh2WI0ah9FM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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