SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f2ff48ff300c45fdb38ad14cf16aa5c737de245e9715e5be5e651cb8f3eeb4ac' 
  AND token = 'l9QQ/NHvpKjCNMRUQVPsg0eZlG71B9FvGizhgxs0PAM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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