SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3aa75517025daa667bc4d9c530e84ba54a7d7f5b90f372dd006fc734690366d6' 
  AND token = 'hgbCPd1L7n0A8gV5NID5nMmmDN25iv550gutj4jaAv4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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