SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3f51f13954cdc704960759a343927b0e4bd5aa124ef05b8ffb17027eaa157b1' 
  AND token = 'by3BwKt674VFLIvctUU+fDn/Qz+UkMimh4duEJVqNXs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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