SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c71f8c97a30b77021b736a136cd0f27fe67d9e252830bcb1881caa6ebfebf4b' 
  AND token = 'Py6sWBppGBTMVIGS9+RCFnm+iv7fAtoltX3tKwZewV8=' 
  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"
    }
  }
}