SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd694a3ddd820d55bbc664909839d009009dcfdee2d11b7f2a96373587d499679' 
  AND token = 'nkV5RkJIRQB5q5hiiFbA1MMkpdV7sedETBDikp+ewXI=' 
  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"
    }
  }
}