SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '476c39a6c5c35edfeca698e4310b14931f50cc672cffe5fb8cab5638bd97f6f2' 
  AND token = 'gwnWK6jAufJlrZi6XvUPS8/ORWSKwxsScYpEvTJPK78=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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