SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '638c63bf0df45d42440822a1f82e3b237d63e813df34aff7518e4fe82cec35af' 
  AND token = 'ynPoJGlgiw/ZvP8LmucqC3h4RMomoaIfTIbGi8MgNHI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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