SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e9fd2bc0a525e6ab82cbb561b877daccb10648324b2e08188dff0e23e3b4c322' 
  AND token = 'IwgUxgT+vCZkYGvaLEgr1592LyTnzPlDHDmBLFMxxkU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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