SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c825d32a3a138019dfc6f329622b476a852537dd17432b7856cebe816d5d8542' 
  AND token = '+dYoQIdA7ULwEWSjaI9WhMknDN19o/mXWMtqO51F4RA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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