SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '855b63092212a5978fb299f63c5d5b024905791cd3f97bdb038795c2f53cc0dd' 
  AND token = 'rN846GvhlHWStBS4w008XjssB+MPb20r93EYN6Reejs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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