SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '126dd6d771cb400659d584053c17db2c653ce1c6e2d5e1c04fff3db8f8a926e9' 
  AND token = 'UaqfnYCUjqiyblZ/CWZQtOgMlKND6gVdlkpl8w3QHug=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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