SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7fef8a2f862387f424f56ea6f4bcf5c90e3b401c59b320b146df15904137a3b' 
  AND token = 'YKQ64i7GnhSpUVKojY3mNg48DlTF6geEOdNlrzPwcFQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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