SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb4d79c6852a471aebccbbec64b995e0545ee079233e736ccebc401ee522f87f' 
  AND token = 'snamMDnugsbkJCCDAAu+pL6Rbp229LkUVKsb+e3qjoQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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