SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec0fad48f6a684c53fcfa5dcc1290c10aa7d0dc45939bff058f7209674526293' 
  AND token = 'kCY/qH8vJGwVYRW8jldVO+3NDMBZo+XMNkyZkbs34wA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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