SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ddd36cc3a34a27f1dfcc02292209977e5c8842e94f5aec15528833e90f0d2b62' 
  AND token = 'XsH7qz20kECJqbD+jlY8ym7K7JxO/bCECZLPcKvqJT4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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