SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78e315012f1ca5377b44f61b54502b48dcfa1874fa996f020408878880303421' 
  AND token = 'zcQWmf+tN6q4vWGRMKrDVlOL6BZXD/gdr45zrQLp6HU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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