SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '346a149b7ce3e3c2ef8c545738690e2ca594f070d6d4ad21f67051600d2655dc' 
  AND token = '6LoHzXAzr5uPBGyHZ+ymvqEU3FhDS3xRYfOkf+/5Pak=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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