SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a541ff8bcf14bca5cb35d0fa04c41358839e047fbed496578f4213823b73017c' 
  AND token = 'bN/XRQM5UniLhc2e/KCg8nLlJNzISX5C6sy/12tUI9U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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