SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3f6328a72e72973d4c03b8158d8f4e71bc8a5045c5927c458c895d9d0f52da0' 
  AND token = 'i7ETveAPKq1IjA0Zbdga3D1BU0lUs/1hPTW4ZOUHvl0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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