SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98ec20eaea67baa959d1d298acfa0c4fc264554e992b762a08005ca86609b896' 
  AND token = 'I89AqUXXNWdlXLFyCVZCiu9BKpVVg5lFDanuQZjLb4E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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