SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9a7b350578264de370db4568c527618f790cb493e0b4900d6e98be2f2499791a' 
  AND token = 'sna6t8Qpdr2znDhmWMtfvpVGzgCM9hh97bvE7NAa0uk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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