SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '789cdd5a7f4d6958fb5b496f80d65e693be338d22c33bdaa38b21a2ca059bb71' 
  AND token = 'mcY6KXwrU563BUf+ALhr+WrG/tZ7U3N7lgRabG35qhI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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