SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '397f21a62489b7df5429cf0956fa0fa764cce8dbc3bff86337d670d2e571fff6' 
  AND token = 'DD3PqE2BY71GcEPZgd+cuvNpH/Q0ChD6ATrLaywK9bs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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