SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '84f97512c2daf9427e924d64f358387961e1b96918acc97344c90c36cada026c' 
  AND token = 'Ee1z+8erBfd7PvaksCTupCklFiOtvUREKgl/lERnIEQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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