SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42346dea921d5e260c2f5e35d9587831319716133778c68226f8794e181ebf0b' 
  AND token = 'nmdsvrcg3Bm4bGk+qjEP+QxWlqL5Tb1E/h6XfAEzp8U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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