SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a3e629a3e4fbddce7bad7fecd99a44f499a107920aba48dcee8faa8c123f509' 
  AND token = 'fmBm4KsF2qaevG5gJnYLJll/0pUBP0skxuLA3a42pOk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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