SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd23ff96f9ef0bbd5099ba0a5b0f971f634f0b30d1e3fa4874277232c918d3f3e' 
  AND token = 'dYg/OP8nNBqKliWh+UfqPn+TK35XAZ5zL/rjX/QoFcM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}