SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ff723008218ce2ebf28879953233af51acfdbcb77a3e256b22b60aa8e49d154' 
  AND token = 'ea80bt+oquUMugrKSUKRt2SN/gumOifBulz+MwWZQzM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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