SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c88ac483c6d97a971eee2987516a3d8905901b744558c2a539192b8c90a9b264' 
  AND token = 'HwtEbP+/eR4fcQWkqndpycz/c62NNhzvNojkMOzwgn8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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